40 
IOWA ACADEMY OP SCIENCE 
Annual Precipitation. 
station 
County 
No, of years 
Annual precipi- 
tation in inches 
Sioux City 
Wondbiiry 
14 
24.61 
Onawa 
Mnunua. 
24 
32.07 
Logan 
Harrison 
37 
33.80 
Rock Rapids 
Lyon 
0 
23.17 
Le Mars 
Plymouth 
7 
28.70 
Council Bluffs 
Pottawattamie 
25 
32!25 
Glenwood 
Mills 
17 
28.69 
Thurman 
Fremont ....... — 
7 
4o!53 
The average precipitations given for the different -stations 
do not approach each other very closely. Sionx City had 
only a little over twenty-fonr inches and the county just to the 
south a little over thirty- two inches, while Plymouth, just to 
the north, had an average of a little over twenty-eight inches. 
The averages are based on shorter or longer periods of years. 
It is probable that an average for a longer series of years would 
increase the precipitation for Sioux City and would decrease 
the average precipitation for Fremont county. It is, however, 
evident that the rainfall is decidedly less in northwestern than 
in southwestern Iowa. As to temperature Fremont and Mills 
counties have a higher temperature than Woodhury, Harrison 
and Monona counties. A difference in temperature of a few 
degrees during the winter months no doubt influences the dis- 
tribution of certain species. A few more inches of rainfall as 
well as sheltered places no doubt determine the distribution of 
some trees. The lowest temperature reached is a more important 
factor than the mean. We And the lowest temperature in Fre- 
mont county in 1909 was — 13°. In Sioux City it was — 17° 
the same year and month, a difference of only 4° Fahrenheit. 
The records show that lower temperatures are more frequent in 
Sioux City than in Logan and Thurman. Attention has been 
called to the native occurrence of the sycamore, red bud and 
papaw in Fremont county. The sycamore is frequently culti- 
vated in Missouri Valley and Sioux City where the species is 
perfectly hardy. The red bud is perfectly hardy in Missouri 
